Punching machine



May 3, 1932 c, TQWLE 1,856,175

PUNCHING MACHINE Filed 001.. 24, 1927 2 Sheets-Sheet l [I J INVENTOR Han/0rd 6K Ibwle,

May 3, 1932. H. c. TOWLE 1,856,175

PUNCHING MACHINE Filed Oct. 24. 1927 2 Sheets-Sheet 2 Patented May 3, 1932 NITED STATES PATENT OFFICE HOWARD C. TOWLE, F COHASSET, MASSACHUSETTS, ASSIGNOR TO BETHLEHEM SHIPBUILDING CORPORATION PUNCHIN G MACHINE Application filed October 24, 1927. Serial No. 228,183.

My invention is directed particularly to those features of punching and allied 1nachines relating to the stripping of the workpiece during the withdrawal of the punch and .5 to gag mechanism whereby the punch may be loosened so as to be easily centered preliminary to the punching stroke.

Referring to the drawings for a description of a specific embodiment of the invention:

Fig. 1 is a front elevation of the mechanism, parts being shown in sections;

Fig. 2 is a vertical section taken along the line IIH looking into the direction of the arrows;

Fig. 3 is a partial plan and section taken through the gag mechanism along the line TIL-III of Fig. 4-;

Fig. 1 is a vertical section of a part of the ac punching mechanism, showing a portion of the gag means, but at right angles to what is shown in Fig. 3 having the gag means in a different operative relation to a punch than is shown in Fig. 2.

Fig. is a vertical. section of a part of the structure taken along the line VV of Fig. 1, showing the means whereby the stripping mechanism is carried by the punch head.

6 is a perspective View of the stripper an mechanism.

The reciprocatory head 10 is slidably supported relatively to the stationary frame 11, this punch head being actuated in the common way by cam 12 mounted on shaft 13 flour-pulled in the stationary frame, there being the ordinary bearing ring 14 surrounding the cam. At the lower portion. of the punch head. punches 15 are mounted in member 16 which is bolted to punch head 10. The means whereby the punches are held either in. tight engagement on the member 16 for the punching operation by or in loose engagement for ease in centering them preliminary to the actual punching, or in such position that they are completely inoperative will be later described when the gag mechanism is set forth.

F rst describing that aspect of my inven tion relating to the stripping mechanism A stripper 17 is provided with a foot 18 adapted to engage the work-piece in the vicinity of the portion to be engaged by the punches 15. This stripping member 17 is bolted at20 to a frame 19, a portion of which is adapted to slide in guides on a forwardly extending portion 21 of reciprocatory head 10. These portions 21 have shoulders 29. upon which shoulders 23 of frame 19 are adapted to rest and be cammed during a certain part of the operation. Plate 24 is slidably mounted in guides 25 of frame 19. Near the lower end of plate 24 a roller 26 is mounted to be engaged by cam 27, keyed to theportion 27 of shaft 13. Rod 28 is affixed to the upper portion ofsliding plate 24, having a sliding en'- gagement with the upper part of frame 19. Interposed between discs 30, one of these discs engaging the upper part of frame 19 and the other engaging wheel 31, is compression spring 30. The desired degree of compression of spring 29 is secured by meansof the adjusting wheel 31 having screw threaded engagement with rod 28.

The operation of the stripping mechanism is more or less obvious. Accordingly, a brief description onlv thereof will be necessary. In Figs. 1 and 2 the apparatus is shown shortly after the withdrawal of the punch from the work. The reciprocatory head 10 is actuated in the usual manner. At the bginning of the downstroke of the reciprocatory head, the stripping device will be carried by the reciprocatory head, frame 19, which is a part of the stripping device resting on shoulders 22 of the reciprocatory head. The stripper is preferably so proportioned that the foot 18 will engage the work-piece prior to the punch in order to hold it firmly in the desired position for the punching operation. When the stripper touches the work-piece its downward movement obviously ceases, the reciprocatory head, however, continuing to move to effect the punching operation. this continued movement naturally producing a gap between shoulder 22 of the reciprocatory head and shoulder 23 of frame 19.

The mechanism is so designed that during the latter part of the downstroke, cam 27 so moves relatively to the roller 26 on sliding plate 24 that this plate reaches its lowermost drawn. from the material thereof.

position at the end, or somewhat before the end of the stroke, the compression of spring 29 and the pressure of the stripper on the work thereby reaching their maxima at this time. During the initial stages of the upstroke of the reciprocatory head, that is, while the punch is being withdrawn from the material of the work-piece, this maximum pressure of the stripper on the work-piece will continue because of the-fact that the thickest part 27 of cam 27 is circular for a considerable angle of movement. in consequence of this action, the stripper holds the work-piece firmly while the punch is being Obviously, the presence of spring 29 will give this supporting action of the stripper on-t-he work-piece a more or less-resilient character. As the upstroke continues, following the withdrawal of the, punch from the material of the work-piece, the gap between the projecting portions 21 ofthe reciprocatory head and shoulders 23 of frame 19 closes, and the frame .l9-with.the attached stripper will be lifted,

the compression on spring29 also being relieved by the thinnerportions of the cam coming into play upon roller 26.

Now directing attention to the other aspect of my1nvent1on,.namely,the gag mechanism. Briefly tlns mechamsmprovidesfor locking thepunch rigidly tothe reciprocatory head 39 of the stirrup piece.

during the punching stroke and-for releasing the punch during the succeeding upstroke, to such an extent -as.t0 render it comparatively loose relative to the reciprocatory head whereby it may be easily centered upon the work-piece, and then automatically locking thepunch upon the succeeding; downstroke.

Shanks 15 of punches, 15', are mounted in opening ifi ofmember 16. 'Each punch is carried bya. stirrup piece 3-9,. shank 15 being slidably mounted in the extended opening The upper portion of each shankis of greater diameter than the. portionin the opening of the stirrup piece and is provided with a pin 41 which engages the upper cam face 40 of the stirrup piece.

Each stirrup piece is. adjustably secured to lug 38 of a gag element32, these elements together constituting, alocking' device for a punch. Theselocking devices, o.ne for each punch, are slidably mounted in slot 33 of member 16, this slot communicating with opening 16. V7 hen pushed forward in slot 33, or to the left, as viewed in Figs..2 and 4, the punches arerestrained from the movement by the limited size of opening 16,'the cam surface 40 movin under the supporting pins 41 to lift the punches, the upper ends of their shan rs approaching the advancing gage element 32. At the most advanced position of the lockinp; devices,the shanks are wedged in locking position between members 32 and 39, as indicated inFig. 2. Obviously,

stroke of the reciprocatory head the locking device is automatically moved into the lockmg position; upon the upstroke of the reciprocatory head, it is automaticaliy moved into an ineffective position but allowing the punch to rest upon the Work in a floating conditlon. The means for effecting these operations will now be given. p p

mach locking device is connectedhymeans of rod 32 to the core 35 of an eiectromagnet, a compression spring 36' being so placed as to force this core backwardl that is in a div rect on to pull the locking oevrce into a completely inoperative position, that-position indicated in dotted linesin Fig. 4. A solenoid 34. partly surrounds the core and is connected with a suitable source of current. W hen the circuit is closed the electromagneticforce produced acts to all the core a. must the force of the spring and thus tends to move the locking c evice into alocking position. Obviously, upon opening the circuit, the spring moves the device into a completely inoperative position- The electromagnets are separateIy perabIe thereby permitting the simultaneous or separate use of the punches. Brackets 37 support the electromagnets upon the reciprocatory head 10.

Upon a shaft 42, supported upon frame- Work 11 by means of brackets 43, are pivoted bell crank levers having long arms 44 norfinally handing,- Vertically and short arms 45 extending horizontally. Reciprocatoiy head 10 isprovided with a plurality of lug-like portions 46 disposed in the same vertical planes as the horizontal arms 45 of the bell crank levers.

Preparatory to a particular punclnng stroke, that is when the reciprocatory head is inits uppermost position, the circuits of electromagnets 34 are closed bythe operator for the particular punches which are to be effective during that stroke, thereby causing the corresponding punch locking and holding devices to move forward into the positions indicated in full line in Fig. 4. In this position the punches are not locked but are floating, the complete forward movement of the locking and holding; devices beingprevented by arms 44 abutting against the front faces of stirrup pieces 39. In this floating position the punches are supported at the lowest points of the stirrup pieces, that is to say in the'regions between cam surfaces40 and 50. Under this conditionthe punches rest upon the work and being in a floating condition the work.

work can be manipulated to bring it into the desired relation to the various punches.

The locking devices for those punches which are to be inoperative for a particular 1 stroke and the circuits for whose electromagnets remain open, occupy the position indicated in dotted lines in Fig. l, springs 36 normally tending to hold the locking devices in their extreme rearward positions. Because of the conjoint action of pins all on the punches and cam faces 50, the punches are then in their most elevated positions and in an inoperative condition. It will be readily apparent that while those punches which are to be utilized in the next downward stroke rest upon the surface of the work, those punches which are not to be utilized are elevated so that they do not touch the work, and thereby confusion to the operator is its is evident, the punches to be utilized during a particular stroke occupy the same positions on the work, after adjustment thereof, as the points on the work where the punching will be accomplished.

Upon the upstroke, lugs 4-6 strike short arms of the bell crank levers thus throwing the long arms a l inwardly to engage the projecting portions 39 of stirrup members 39, thereby pushing the locking device-s rearwardly to such an extent as to again restore the punches to their floating condition. At the end of the upstroke the punches are floating and with their lower ends touching the For the next downward punching operation obviously the circuits of the electromagnets to control the holding and locking devices for those punches which are to be inoperative, will be opened and those which on the previous stroke were inoperative but which are now to be employed will be closed.

It should he noted that there are three distinct positions of the punches First, the completely inoperative position, when the electric circuits in the electromagnets are open and the springs have acted to withdraw the elements 32 from above the punches and with such punches held in their uppermost position in Virtue of the action of cam second, when the reciprocatory head is in its uppermost position and the circuits for the electromagnets closed, the punches now being held so that their ends rest upon the work but with the locking device inetlective to lock them rigidly to the head, arms 44 preventing the locking means becoming eti'ective; and third, the position where the punches are elevated by cam 4-0 to lock the punches rigidly to the head, which position results from the downward movement of the head and the restraining effect of arms 44 on the locking and holding devices being removed.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is: i

1. In a punching mechanism, a reciprocating head, a plurality of punches, means for locking each punch to the reciprocatory head, means normally tending to render such locking means inoperative, means releasable by the operator acting counter to said last mentioned means tending to bring the locking means into effective operating position, and restraining means for preventing the locking means moving into full locking position releasable by the downward movement of the reciprocatory head.

2. In a punching mechanism, a reciproca tary head, means for looking a punch to the reciprocatory head, means for holding the punch in a floating condition with its lower end resting on the work while the reciprocatory head is in its uppermost position, and means releasable upon the downward movement of the head to lock the punch rigidly thereto.

3. In a punching mechanism, a reciprocatory head, means normally tending to render the punches inoperative and to hold them in such position that their lower ends are above the work, means releasable by the operator acting counter to said last mentioned means to lower the punches in a floating condition and with their lower ends engaging the work, and means effective upon the downward movement of the reciprocatory head to lock the punches rigidly to the head.

4. In a punching mechanism, a reciprocatory head, means normally tending to render the punches inoperative and to hold them in such position that their lower ends are above the work, means releasable by the operator acting counter to said last mentioned means to lower the punches in a floating condition and with their lower ends engaging the work, means effective upon the downward movement of the reciprocatory head to lock the punches rigidly to the head, and means actuated by an upward movement of the reciprocatory head to restore the punches to a floating condition with their lower ends engageable with the work.

In testimony whereof I hereunto afi'ix my signature.

HOWARD C. T OVVLE. 

